Industrial robots are often uses for carrying out a process on a workpiece. The process is, for example, painting or welding of a piece of a car. The robot is programmed to follow a path during the processing. A robot controller controls the movement of the robot in accordance with instructions in a stored control program. The process tool used by the robot during the processing, such a paint gun or a welding gun, is usually controlled by a separate process controller. The process controller and the robot controller are usually run on separate processors, but can be mounted in the same rack. However, it is also possible that the process controller and the robot controller are integrated and run on the same processor.
Sometimes during processing, process errors occur, such as insufficient paint flow. The process controller detects that a process error has occurred and stores the errors in an error log list stored on the process controller. The error list contains information on the type of error and the point in time when the error occurred. Upon a request, the error log list is presented to a user. The error log list is, for example, presented as printed list or presented on a display connected to the process controller. Some of those errors are occasional and occur randomly and there is no connection between the errors. However, some errors are related to the position of the robot. Those errors repeatedly occur at the same position along the robot path. The cause of such errors can be hard to find because it is often difficult to observe visually exactly when and where the error occurred.